VW T5 - Central locking SAFE indicator / status problem...

AlfT5 · Apr 9, 2025

Vehicle has these issues:
-SAFE indicator lamp not blinking when locked, this is a recent development as it worked a few months back.
-Erratic behaviour of both cab door locks.

The SAFE lamp works fine using sequential output test so the module can control it.

In VCDS, when locked via the fob, I see safe status for the left sliding door (F222) and rear door (Rear Lid Feedback), but only locked status for the cab doors.

Bit confused here? Wiring diagram (attached) shows an unused "safe" terminal at pin 3 on each lock.

I've metered T23/9 and T23/2 with the module unplugged, and on both I get:

-180 Ohm to ground with the relevant door locked
-1.2 Ohm to ground unlocked
-0.9 Ohm door open (red herring I think, not a readable difference)

So... any ideas what's going on here? How is the module meant to detect "safe"? Should these statuses show "safe" for the cab doors when locked, and so what is the signal that communicates that to the CCM?

TIA!

Autoscan follows...

Code:

Wednesday,09,April,2025,20:19:41:61254
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 8.1 x64
VCDS Version: 25.3.0.4 (x64)  HEX-V2 CB: 0.4660.5
Data version: 20250311 DS365.0
www.Ross-Tech.com


VIN: WV1ZZZ7HZ6H083239   License Plate:
Mileage: 161940km-100624mi   Repair Order:



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 7H (7H - VW Transporter/Multivan (2003 > 2010))
Scan: 01 02 03 08 09 0B 0D 15 16 17 18 19 1C 22 2D 37 45 46 47 56
          57 6E 76 77 78 7D
 
VIN: WV1ZZZ7HZ6H083239   Mileage: 161940km-100624miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 038-906-016-AXB.clb
   Part No SW: 038 906 016 M    HW: 028 101 185 6
   Component: R4 1,9L EDC 0000SG  6278 
   Revision: 12345678    Serial number: VWZ7Z0E3173167
   Coding: 0000031
   Shop #: WSC 02756 785 00200
   VCID: 1E620736ECA9219A9DB-5160
   VINID: 9E606AAAA1D8A8660020308324EB3FED33

No fault code found.
Readiness: 0 0 X X X

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 7H0-907-37x-ASR-F.lbl
   Part No: 7H0 907 379 E
   Component: ASR FRONT MK25      0103 
   Coding: 0007205
   Shop #: WSC 02756 785 00200
   VCID: 372CF292635370D27ED-5140

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect.        Labels:. 7H0-937-049.lbl
   Part No: 7H0 937 049 M
   Component: BORDNETZ SGVER 1.0  0901 
   Coding: 0000004
   Shop #: WSC 02737 785 00200
   VCID: 3C26EDBE5A75538A93F-5140

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 6Q0-909-605-VW5.lbl
   Part No: 1C0 909 605 A
   Component: 3B AIRBAG VW51      0008 
   Coding: 13122
   Shop #: WSC 02756 
   VCID: 221A33C6DDD1057AB93-5140

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 7Hx-920-xxx-17.lbl
   Part No: 7H0 920 951 M
   Component: KOMBI+WEGFAHRSP VDO V02 
   Coding: 01411
   Shop #: WSC 00001 
   VCID: 3632FF96615989DA65B-5140
   WV1ZZZ7HZ6H083239     VWZ7Z0E3173167

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.clb
   Part No: 6N0 909 901
   Component: Gateway K<->CAN    0001 
   Coding: 00006
   Shop #: WSC 02737 
   VCID: 70BE098E43BDE7EA7F7-5140

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 7H0-959-433.lbl
   Part No: 7H0 959 433 B
   Component: C2L Komfortgerát     0004 
   Coding: 00021
   Shop #: WSC 02756 
   VCID: 323AC3868D3195FA493-4B1E

No fault code found.

End----------(Elapsed Time: 06:24, VBatt start/end: 14.6V/14.6V)-----------
------------------------------3 Faults Found-------------------------------

AlfT5 · Apr 12, 2025

Ok!

So I went most of the way to the bottom of this rabbit hole. Ill share such info as I've been able to figure out now...

There are two microswitches inside the electrical clamshell part of the lock body, as well as a 180 Ohm resistor. These three components are a group that all interact with the pin 5 conductor from the CCM and ground only.

Number 1 is responsible for the locked / unlocked status of the door.
-When it is pressed, by the lock carriage in the unlocked position, a direct path to ground at pin 7 is open.
-When it is not pressed, a path to ground via the 180 Ohm resistor and the Number 2 switch is open.

Number 2 communicates the "SAFE" status to the CCM. Pressing it alone is sufficient for VCDS to show "safe" in the relevant door status field.
-When it is not pressed, it connects one leg of the 180 Ohm resistor to ground, completing that circuit.
-When it is pressed, by the deadlock mechanism being in the engaged position, the switch is open and no path to ground exists.

Here are those pathways in graphical form.

To boil this right down, as far as the CCM is "looking" for anything it will read:
"Unlocked" if pin 5 is grounded
"locked" if pin 5 is grounded via a resistance of 180 Ohm
"Safe" if pin 5 is OC / no path to ground.

It amused me that this means the door will show as "SAFE" with the lock unplugged... but yes it will do that. Hmm... :thumbs:

Testing revealed my fault is the common one, the motor having become weak and no longer able to make the torque required to operate the deadlock. It can still (erattically) lock and unlock the door but the deadlock requires more force from it. Everything else is working correctly.

Now a bit more on the mechanical side of this system.

This green wedge shaped bit of plastic is the dreaded deadlock.

A pin on the bottom of the lock carriage rides in these grooves.
The "pin carrier" is threaded directly onto the drive axle, but pushes the carriage back and forth via springs.

All being well, starting from the unlocked position (Pin near to 1), one electrical pulse of locking polarity will move the pin down the groove towards 2.
The carriage will run out of travel when the pin is roughly parallel with L, at which point the motor begins to compress the carriage springs allowing the pin to move further.
This further movement allows the pin to reach 2, while indexing the deadlock over to the right.
At the end of the pulse, the spring force causes the pin to retreat slightly (and the motor to run backwards briefly), it's caught by the wedge shape on the groove, indexes the deadlock slightly further to the right and ends up at L, the normally locked position.

From position L, a pulse of unlocking polarity gives an easy route for the pin back to 1, moving the deadlock back to it's unlocked position.

Also from position L, a second pulse of locking polarity will once again compress the springs, and drive the pin to position 3, indexing the deadlock all the way into it's engaged position.
At the end of this second pulse I believe the pin will come to rest to the left of position L, held by this small ramped plastic tang.
In this position, the plastic lug (beneath 2 and 3 in the photo) is engaged with the carriage itself, blocking it's movement. I have not yet fathomed how or why this disables the internal door handles? If you could "feel" them when deadlocked but they would break before opening the door that would make sense, but you can't...

To disengage the deadlock via an unlocking pulse, the motor has to simultaneously generate enough force to compress the springs in the carriage (which can't move, because of the deadlock) AND push down the plastic tang to the left of L, AND overcome the friction between the carriage and the locking tab on the deadlock (which it is actively pushing together :facepalm:

) This is a big ask and it's kinda obvious how many of these tend to get stuck shut. Probably the most viable route will be to apply voltage in unlock polarity continuously, and bang on the door from outside with a rubber mallet adjacent to the door handle, then replace the complete unit.

Alf

VW T5 - Central locking SAFE indicator / status problem...

AlfT5

Verified VCDS User

AlfT5

Verified VCDS User

We value your privacy